A 9-year-old 12-lb spayed female Boston terrier was presented to the emergency service at Angell Animal Medical Center for evaluation of lethargy and anorexia of one day's duration. The owners also reported progressive hindlimb ataxia.

The owners described the dog's hindlimbs as shaky for a few days, and by the afternoon prior to presentation, the dog could only take a few steps before collapsing. During the collapsing episodes, the dog vomited and urinated but did not appear to lose consciousness, according to the owners. The owners reported that there were no clinical signs of neurologic or cardiovascular disease two days before presentation.

HISTORY

Two weeks before presentation, the dog received its annual examination from its primary care veterinarian and was prescribed clindamycin (3.1 mg/kg orally twice daily) for treatment of a suspected tooth root abscess. The dog received the drug until vomiting began the day before presentation.

Long-term medical history included documentation of calculus and periodontal disease by the primary veterinarian, but a dental procedure was not pursued. A grade II heart murmur was also first diagnosed one year before; however, diagnostic tests, such as thoracic radiography or an echocardiogram, were not performed at that time to further evaluate and characterize the murmur.

An oral examination revealed significant periodontal disease with severe dental calculi of the canine, premolar, and molar teeth as well as erythema of the gingiva characteristic of gingivitis. There was also gingival recession with root exposure of the maxillary fourth premolars and molars.

Neurologic examination results showed the patient to be mentally dull with a right-sided head tilt. The dog had pelvic limb ataxia, generalized paresis of the hindlimbs, and conscious proprioceptive deficits to the right pelvic limb. The patient would also sit with spinal pressure to the cervical and lumbar spine.

DIAGNOSTIC TESTS

Table 1: Abnormal Laboratory Results

Initial diagnostic tests included a complete blood count (CBC), serum chemistry profile, and venous blood gas analysis. The CBC revealed a normal white blood cell count; however, evaluation of a blood smear by a veterinary pathologist confirmed the presence of 1+ toxic change. Red blood cell morphology and platelets were adequate on the smear. The patient was also lymphopenic and anemic (Table 1). Abnormal serum chemistry profile values included elevated alkaline phosphatase activity, hypocalcemia, hyponatremia, hypochloremia, hypomagnesemia, and increased anion gap (Table 1). All the changes on the serum chemistry profile were considered mild. Despite a low total calcium concentration, the ionized calcium was within normal limits on the venous blood gas analysis. The only additional information from the venous blood gas analysis was mild respiratory alkalosis as indicated by the elevated pH and the low partial pressure of CO2 (Table 1).

Thoracic radiography was attempted the evening of presentation but was aborted because of a collapsing episode. During the episode, the patient vomited and urinated, and its mucous membranes became pale.